Image converter tubes



. March 4, 1958 yFiled Feb. 19, 1948 C. S. SZEGHO ET AL.

IMAGE CONVERTER TUBES 2 Sheets-Sheet 1 ,www

V(Ittomeg March 4, 1958 c. s. szl-:GHO ET AL 2,825,834

IMAGE CONVERTER TUBES Filed Feb. 19, 1948 2 Sheets-Sheet 2 FIG. 2. FlG. 5

3 llllll or CONSTANTIN S. SZEG W|L L|AM O. REED United States Patent O F IMAGE CONVERTER TUBES Constantin S. Szegho and William 0. Reed, Chicago, Ill., assignors `to The Rauland Corporation., Chicago, Ill., a corporation of Illinois Application February 19, 1948, Serial No. 9,495 9 claims. (Cl. 313-66) This invention relates to new and useful improvements in photoelectric devices for storing and converting intelligence.

One object of the invention is to simplify the construction of the device by making the envelope in the form of a substantially straight cylinder. A cathode and a liuorescent screen are mounted on or near the two ends of the cylinder and the storage electrode is mounted between the two.

According to one feature of the invention, the storage electrode is formed on a thin conducting surface, e. g. a thin film of aluminum which faces the cathode and is traversed by the beam released therefrom.

According to another feature, the cathode is in the form of a layer of photosensitive material deposited on one end of the cylindrical envelope. The signals to be stored are conveyed to the cathode as light radiations, producing a photoelectronic beam which impinges on 4the storage electrode and produces an energy distribution therein corresponding to the original intelligence.

These and other features of the invention will more clearly appear from the claims, the detailed description of an embodiment and the drawing in which:

Fig. 1 diagrammatically illustrates an embodiment of the invention;

Fig. 2 is the front elevation of a fragment of the storage electrode of Fig. 1;

Fig. 3 is a section on the lines 3-3 of Fig. 2; and

Fig. 4 is a front elevation of a fragment of an alternative storage electrode.

As shown in Fig. 1 the storage electrode is housed within an evacuated envelope 1 of glass or other suitable material. The envelope is substantially cylindrical with flat or slightly curved ends 2 and 3. A sloping window 6 in the side wall of the envelope permits the penetration into the device of rays of light, infra-red or utra violet, from a source 4 through a filter 5 which excludes ambient visible light from the envelope.

A semi-transparent photo cathode 7 is mounted on the end wall 3 through which radiation from an object may be focused. The spectral response of this photo cathode preferably has a maximum in infrared.

End 2 of the envelope carries a uorescent screen 8. The screen as well as adjacent portions of the envelope side wall are covered by an aluminum lm 9 functioning as a light reflector, and barrier to slow moving electrons and ions. It also assists in protecting the screen from the cesium vapors formed during the processing of the tube.

The storage electrode 20 is mounted between the two ends of the cylinder 1. The electrode of Fig. 2 comprises a film of aluminum 10 on which is deposited a photo cathode 11, e. g. silver-cesium-oxide, covered by a mosaic of insulating material 12, such as quartz. The aluminum iilm being opaque prevents light from light source 4 from falling onto photo cathode 7.

Fig. 4 shows another method of arranging insulators 3.2 close to the photosensitive material of cathode 11.

Patented Mar. 4, 1958 ICC On an electron permeable continuous insulating, plate 17 diagonal conducting lines 18 are ruled or deposited and photosensitive material 19 is deposited on the assembly. Plate 17 may be made of aluminum oxide or thin opaque glass. Lines 18 must be interconnected e. g. by conductive lines 21 and each globule of photosensitive material must make contact with at least one line.

Photoelectrons emitted by photo cathode 7 to which negative potential of 10,000 volts isy applied are accelerated and focused on the storage electrode by suitable electro.- static or electromagnetic means e.- g. electrodes 13,-to which negative potential of 6,000 volts is applied, and 14, to which negative potential of volts is applied, mounted in the left-hand compartment between the cathode and the storage electrode, or an electromagnetic focusing coil. In the assembly of Fig. 2, the high speed electrons will pass through the aluminum lm 10, to which negative potential of 100 volts is applied, and the photo surface 11 to strike the insulating material 12 at the proper velocity to store charges on it. Any electrons that pass through layer 12 will be collected on a grid 15 which may be at ground potential or negative 100 volts, depending how switch 19 is connected. The grid is mounted within envelope 1 to the right of the storage electrode and parallel therewith.

During storage the positive potentials maintained on aluminum lm 9 and on accelerating and focusing electrodes 16 in the right-hand compartment of the envelope are reduced to bar electrons from screen 8.

When it is desired to read the signals which have been stored, infra-red light from source 4 is turned on the storage electrode which will release photoelectrons from 11 (Fig. 2) with a density distribution determined by the charges on mosaic 12. A uorescent picture will thus be produced on screen 8 of the intelligence which was originally impressed on cathode 7. Accelerating and focusing voltages of 10,000 volts on aluminum lilm 9 and 4,000 on electrode 16 are applied during the reading time.

The mosaic 12 may be cleared of all charge or brought to uniform potential, by the application of suppressing voltages on electrodes 15 and 16 while layer 11 is subjected to constant illumination so as to set up a space charge in front of 12.

What is claimed is:

1. A device for storing intelligence comprising an envelope, a cathode of photoelectric material in the envelope, a screen of fluorescent material in the envelope, a storage electrode in the envelope between the cathode and screen, said storage electrode having a metal surface permeable to electrons facing the cathode, a layer of pho tosensitive material on said metal surface and a mosaic of insulating particles on said layer facing the screen, and a window in the side Wall of the envelope for exposing said layer to radiation.

2. The storing device according to claim 1, and in which the cathode and storage electrode are parallel.

3. The storing device according to claim 2, and in which the cathode and storage electrode are aligned.

4. The storing device according to claim 1, and in which the cathode and screen are parallel.

5. The storing device according to claim 4, and in which the cathode and screen are aligned.

6. The storing device according to claim 1, and in which the cathode, screen and storage electrode are parallel.

7. The storing device according to claim 6, and in which the cathode, storage electrode and screen are aligned in the order named.

8. A device for storing intelligence comprising a substantially cylindrical envelope having parallel transparent ends, a cathode of photoelectric material applied to the inside of one end, a screen of fluorescent material applied to the inside of the other end, an aluminum lm covering the inside surface 0f the screen and contacting the side wall of the envelope adjacent said other end, a storage electrode in the envelope between the ends and parallel therewith, said storage electrode having an aluminum film facing the cathode, a layer of photo-sensitive material on the last-mentioned ilm and a mosaic of insulating particles on the last-mentioned layer facing the uorescent screen, electron-accelerating and focusing means be tween the cathode and the storage electrode and also between the latter and the screen, a grid adjacent the mosaic face of the storage electrode and between it and the screen, and a window in the side wall of the cylinder exposing the layer of photosensitive material to radiation.

9. A device for storing intelligence comprising an envelope; a cathode of photoelectric material in the envelope; a screen of fluorescent material in the envelope; a storage electrode in the envelope between the cathode and screen, said storage electrode comprising electron permeable conductive material facing the cathode, photo sensitive material attached to the conductive material and insulating material attached to one of said last mentioned two materials; and a window in the side wall of the envelope for exposing said second layer to radiation.

References Cited in the file of this patent UNITED STATES PATENTS 2,297,478 Kaliman Sept. 29, 1942 

